Radiation Protection for Physicists

rpubs.com/sofiaskyttner

Any question = good question!

Ministry of Information Photo Devision Photographer

Justification & Optimization

Nevit Dilmen

Toolkit to handle following issues

• Protection quantities
• Risk: late and acute effects
• Distance, time & shielding
• Categorization of staff and rooms
• X-ray techniques that yield high doses
• Special patient subgroups
• Radiation safety authorities & organizations
• Radiation related accidents & research

• New HOMEMADE sign at the MR dep
• “Välkommen till Magnetröntgen”
• What do YOU say…?

Թագուհի Սաղաթելյան (Own

Ionizing Radiation

• Interventional radiology
• Diagnostic radiology
• Nuclear Medicine
• Radiation treatment

Non-Ionizing Radiation

• MR
• Ultrasound

• Probably extra radiosensitive, avoid working with X-rays
• Please, use double aprons (strålskyddsförkläde)
• Not possible to perceive ionizing radiation

Brookhaven National Laboratory

Sofia Skyttner

Doug Sim

Sofia Skyttner
Example

CT head examination

• Absorbed dose to brain = 50 mGy
• Equivalent dose to brain = 50 mSv
• Effective dose for exam = 2 mSv

Doug Sim

Read more: ICRP 103 (2007)

(*) Adrenals, Extrathoracic region, Gall bladder, Heart, Kidneys, Lymphatic nodes, Muscle, Oral mucosa, Pancreas, Prostate (M), Small intestine, Spleen, Thymus, Uterus/cervix (F)

Read more: ICRP 103 (2007)

Effective dose for comparing…

• …different diagnostic procedures
• …similar procedures in different hospitals and countries
• …different technologies for the same medical examination

Organ dose for…

• …detailed retrospective dose and risk assessments after exposure of individuals
• …epidemiological studies (i.e. study and analysis of the patterns, causes, and effects of ionizing radiation in defined populations)
• …accidents involving ionizing radiation

(*) Comparable to exposure during transatlantic flight

X-ray techniques that yield high doses

• Computed tomography
• Angiography & intervention

Of special concern due to inclusion of healthy individuals

• Mammography screening
• Medical research studies

Patient groups that require special attention

• Pregnant women
• Pediatric patients

Diagnostic Standard Dose

• DSD, Diagnostisk standarddos
• Delivered by hospitals

Diagnostic Reference Level

• DRN, Diagnostisk referensnivå
• Recommendations by authorities

There are no dose limits regarding patients,
but irradiation must always be justified and optimized

Swedish Radiation Safety Authority

Strålsäkerhetsmyndigheten (SSM)

Strålskyddslagen (1988:220)

• 1 § Humans, animals and environment shall be protected to the harm of radiation

• 2 § The law applies both ionizing and non-ionizing radiation

Strålskyddsförordning (1988:293)

Föreskrifter (SSM FS YYYY-XX)

• SSM FS 2008:11 Strålskärmning av lokaler
• SSM FS 2008:20 DSD och DRN
• SSM FS 2008:31 Röntgendiagnostik
• SSM FS 2008:34 Nuklarmedicin
• SSM FS 2008:35 Medicinsk verksamhet med strålning
• SSM FS 2008:42 Upphandling
• SSM FS 2008:51 Skydd av arbetstagare och allmänhet
• SSM FS 2008:52 Externa personer

(FS = Föreskrift)

Read more: http://www.stralsakerhetsmyndigheten.se/Publikationer/Lista/?q=%2bhidden:meta:category:Publikationer%2520AND%2520hidden:meta:category:Publikationstyp;F%C3%B6reskrift%2520AND%2520hidden:meta:category:%C3%84mne;V%C3%A5rd%2520AND%2520hidden:meta:category:Utgivare;SSM&uaid=6C45ACB4B6A92BC35CD28764E5A58211:3139322E34342E3234322E3139:5247841952137539008

• SSM Report 2009:03 National Survey on justification of CT examinations in Sweden
• SSM Report 2010:14 Patientdoser från röntgenundersökningar i Sverige (2005-2008)
• SSM Report 2012:23 Samlad strålsäkerhetsvärdering av hälso- och sjukvård
• SSM Report 2013:11 Mätmetoder för bestämning av stråldoser till ögats lins

UNSCEAR - United Nations Scientific Committee on the Effects of Atomic Radiation
Assess and report on levels and effects of ionizing radiation exposure

IAEA - International Atomic Energy Agency
Safety fundamentals, requirements, guides & practices

ICRP - International Commission on Radiological Protection
Providing recommendations and guidance on all aspects of (ionizing) radiation protection
Publications: http://www.icrp.org/publications.asp

IAEA

AAPM - American Association of Physicists in Medicine

RSNA - Radiological Society of North America

ACR - American College of Radiology

IRPA - International Radiation Protection Association

IPEM - Institute of Physics and Engineering in Medicine

…and many more!

brian0918

The probability of the effect occurring,
increases with dose, but not its severity

Stephen David Williams

LNT model, from Hiroshima/Nagasaki data

Read more: BIER VII Report

Formal system for a feasible and structured approach to radiation protection!

To assess dose…

…use reference anatomical and physiological models of man

To assess hazards…

…use molecular and cellular studies

To assess probability of detriment…

…use animal experiments; epidemiology

Read more: ICRP 103

Lamiot

Contradictory results…!

Lawrence Berkeley National Laboratory
B - the precautionary principle (försiktighetsprincipen)!

Read more: BIER VII Report

NASA Goddard Space Flight Center (left)

• Category A: controlled area (kontrollerat område)
• Category B: supervised area (skyddat område)
  

B (risk to exceed effective dose 1 mSv/year)

• Nurses & physicians in anesthesia/intensive care
• Surgery nurses & surgeons (C-arm)
• Radiographers & radiologists (CT/conv X-ray)
• Biomedical scientists (pediatric angio)
• Engineers & medical physicists (all modalities)

A (risk to exceed effective dose 6 mSv/year)

• Surgeons/radiologists/nurses (angio-/intervention)

Effective dose

• staff, 20 mSv/year (5 mSv: investigation)
  

(patient famiily member: 1 mSv/year, patient: no dose limit)

Equivalent dose

• fetal dose, 1 mSv/pregnancy
• eye lens dose, 20 mSv/year
• skin & extremities, 500 mSv/year
  

Sofia Skyttner

Rakesh Ahuja, MD
Radiation induced catharact, equivalent dose > 0.5 Sv

The severity of the effect occurring increases with dose, but not its probability

Först till kvarn får först mala…?

• Lead aprons for everybody?
• Mobile shields…?
• Not enough lead glasses…!

Lourdes Cardenal

• No cracks…?
• Lead equivalence (0.25/0.35/0.50 mm)…?
• Covering…?
  
  Ted Eytan

• New hybrid X-ray equipment
• Time for first patient
• What is missing in the image…?
  

Unnecessary irradiation of staff

Pfree2014

• Physician and nurse at intensive care patient
• Patient beds close to each other
• Radiographer takes X-ray without shields…!
  

Unjustified irradiation of staff and adjacent pat

Linda Bartlett, National Cancer Institute

Exception: neonatal examinations

• Anesthesia nurse prepares anesthetic equip
• Radiographer no 1 prepares pat for CT
• Radiografpher no 2 starts CT exam
• Anesthesia nurse in room during CT overview image

Unjustified irradiation of staff

DiverDave

• Radiographer 1 forgets delay (50s) before CT exam
• Radiographer 2 next to patient for IV injection
• R 1 exposed without apron, but with dosimeter

Unnecessary irradiation of staff

… (left), Public Domain (right)

Sofia Skyttner
Läs mer: ICRP Publication 60

Especially during first trimester!

Image Editor
Read more: ICRP Report 84

• Contact your medical physicist
• Personal (monthly) dosimeter
• Always right to avoid working with ionizing radiation

Avoid working close to patient at:

• Angiography/interventional systems
• Computed tomography systems
• C-arms (large body)

Dennisthemonkeychild (left), Sofia Skyttner (right)
Read more: ICRP Report 85

Sofia Skyttner

Jan Ainali (left), Public Domain (right)

Female patients in fertile age shall always be
asked for pregnancy before X-ray!

• Female pat in fertile age, vomiting for 10 days
• Gastroscopy without remark, day 1
• Rad ask for CT-abdomen, day 2
• Radiographer do the exam
• Exam shows nothing remarkable
• Finally physician asks for pregnancy test, pat pregnant…!

1) Unjustified radiation of patient (and fetus)
2) Pregnancy question failed (three times…!)

X-ray department shall inform medical physicists about the examination if…

• …fetus was either in or partly in radiation field
  
• …fetus was not the patient
  

James Heilman

Generally fetus dose is: < 0.1 mSv @ conv X-ray & < 10 mSv @ CT exams

Early/mid pregnancy

Fetal dose < 100 mSv: Termination of pregnancy NOT justified based upon radiation risk
Fetal dose 100-1000 mSv: Magnitude and type of fetal damage depend on dose and stage of pregnancy, physician decision should be based upon individual circumstances

Late pregnancy

Fetal dose < 1000 mSv: Not likely to result in malformations or birth defects

Read more: ICRP 89

Kenny Louie

LK Wagner

Functional loss of irradiated organ or tissue, threshold dose exist, appear after days/weeks

Read more: IAEA Rad Prot in Cardiology

• DAP - Dose-Area Product (Gycm²)
• AK - Air-KERMA (mGy)
• PSD - Peak Skin Dose ≈ AK
• CTDIvol - Volume Computed Tomography Dose Index (mGy)
• DLP - Dose Length Product (mGycm)

Note:

DAP unity prefix can vary between vendors…!
Ex: Gycm² , mGydm², etc…

Note:

2000 mGy is fractional target dose at radiotherapy

Interventional cardiac procedures

1 Inform patient, dose report to medical physicist
2 Inform patient, referral to dermatologist

Sofia Skyttner

Exception: neonatal procedure where pat is placed directly on the detector in AP-position

…and if possible:

• Normal dose level (avoid high dose)
• Low pulsed radiation (avoid continous/30 images per sec)

Sofia Skyttner
Read more: Geijer et al Eur. Radiol. 12 (2002)

紫流 (left)
All exams should be justified and optimized!

X-rays in medical imaging should do more good than harm and
benefit-to-risk-ratio should be kept…

…As High As Reasonably Achievable (AHARA)

Individual (or societal) benefit should
be higher than the detriment it causes.

Read more: ICRP 103

Optimization is a cyclic multidisciplinary process primarily involving:

• Radiologist
• Radiographer
• Medical physicist

Without loosing diagnostics in image quality
patient dose should be kept…

…As Low As Reasonably Achievable (ALARA)

Choosing between image modalities, diagnostic tasks, optimization strategies & dose sparing techniques

Read more: ICRP 103

Radiologist + medical physicist + radiographer + …

Craig Taylor
… + surgeon + surgery nurse + medical engineer + contact person + radiation agent (strålskyddsombud) + remittent (regarding referals) + intensive care nurse + …

• X-ray grid (raster) breakes in afternoon
• Engineer says delivery tomororrow
• Radiographers are informed…
• …but during night shift: grid is re-used…!

X-rays of three pat until radiologist complains about image quality…!

BrokenSphere

• Radiographer wants to CT scan additional 2 cm
• Pushes the button “one more”
• Med phys discover CT exam with 41 helical series

Unjustified irradiation of pat,
each keystroke = 0.5 mm scan with 20 mm collimation…!

Sgt. Cecilio M. Ricardo Jr.

James Heilman

Radiation shield…!

Physically fit patient = malnourished patient…?

Public Domain

CBS Television Network Press Information

Less patient (and staff) dose!

Sofia Skyttner
i.e. adjusting scan lenght

Improved image quality & less patient (and staff) dose!

Yale Rosen
i.e. adjusting X-ray beam length and width (inbländning)

• Compression (a.k.a. kompression)
• Improved image quality
• Less patient (and staff) dose
  

National Cancer Institute, Bill Branson

The Great American Disconnect

• Worsening image quality (photon starvation artifact)
• Increased dose to skin-deep frontal organs

… (left), hajime yoneya (right)

Worse image quality (patient out of field artifact)

… (left), Klafubra (right)

Shadows and streaks (movement artifacts)

• Pat with cervical spine collar hiding necklace and earrings
• Pat has zippers in sweatshirt, and carries errings

Citation

“Pat face and ears are full of piercing…!”

George Gastin

NIH (left), Radiopedia (right)
Dark and light streaks, increased noise (metal artifacts)

Ojixt

Dedicated equipment that allow for

• High kV-short exposure time techniques
• Easy grid (raster) removal
• Flexible AEC (chamber selection)

Special care

• Consider additional beam filtration
• Avoid antiscatter grids for the smallest children, or use low ratio grids (8:1)
• Use low dose detectors (i.e. high DQE digital detectors)
• Use low dose fluoro (possibly replace conv X-ray)
• Use TCM in CT and/or scan protocols adjusted to age/size
• Use gonad shield for boys, not for girls & neonatal patients

Electronic management!

Check box: Radiation related accident
Check box: X-ray

Avoid blaiming the messanger!

• Radiographer's dosimeter shows increased staff dose
• Chech routine: radiographer always behind shield
• Medphys measures lead equivalence: ordinary glass…!
• Cleaning staff asked her husband for help regarding glass breakage…!

Unjustified irradiation of staff

• Radiographer finds dose levels high
• R contacts medphys
• Vendor has changed CT protocols…!

Unnecessary irradiation of pat during couple of days

ChumpusRex

• Medphys tests the AEC of a CT system
• Medphys forgets to restore the CT afterwards
• Nobody notices this…
• …but medphys when returning a couple of weeks later

Unnecessary irradiation of about 100 pat

A. T. Service

• Radiographer asks for pat to drink 1.5 l water
• Emergency nurse forgets to tell intensive care nurse
• Intensive care nurse forgets to ask radiographer
• X-ray taken with bad image quality

Not optimized examination of pat

Imperial War Museums

• Ward nurse delivers pat for CT exam
• Chatty staff, “messy”, only forename
• “Is this Amelie?”, “Yes, this is Anneli”
• CT -/+ ivk exam started, already contrast in kidneys…!

Unjustified irradiation of pat

Juhan Sonin

• Ward delivers pat for CT exam
• Radiographer asks “Is this Frans?”
• Ward nurse + pat answ “Yes”
• Radiographer asks for ID no, pat answ with birth year
  

Unjustified irradiation of pat.
Physician noticed wrong pat being examined.

United States Navy, Seth Rossman

• Radiographer calls for supplementary X-ray
• Transport service pick up pat from ward
• Transport deliver pat with one word “supplementary”
• Radiographer takes X-ray without asking for name and ID no

Unjustified irradiation of pat that had took over ward room, ID bracelet necessary!

Editor5807

• Pat from emergency room to X-ray room
• Radiographer scans ID bracelet without asking for name & ID no
• Radiographer takes one X-ray, pat protests: not left hand, right…!

Unnecessary irradiation of pat, pat has wrong ID bracelet

OpenStax

• Surgeon wants to save C-arm images
• Presses left foot pedal
• Left foot pedal = high dose

Unjustified irradiation of pat, education necessary

E-Sergipe

Sofia Skyttner

Flazingo Photos
Strålskyddskommitté- & Etikansökan

Radiation Protection Organization = Multiplication Table

Adrianogon

Anthony Cramp